Fig. 7. X-ray crystal structures of T. thermophilus RNAP with ribo- and deoxyribonucloside substrates.

Crystallographically observed binding poses of CMPCPP (a, b), 2′dCTP (c), and 3′dCTP (d) in the active site of T. thermophilus RNAP. Magenta numbers are interatomic distances in Å. Panels a and b were prepared using PDB ID 4Q4Z¹⁸. Pre-catalytic complexes in c and d were trapped due to the low reactivity of deoxyribonucleoside substrates and the slow catalysis by RNAP in crystallo⁵². Source data are provided as a Source Data file.